NS-3 based Named Data Networking (NDN) simulator
ndnSIM 2.0: NDN, CCN, CCNx, content centric networks
API Documentation
unicast-udp-transport.cpp
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
27 #include "udp-protocol.hpp"
28 
29 #ifdef __linux__
30 #include <cerrno> // for errno
31 #include <cstring> // for std::strerror()
32 #include <netinet/in.h> // for IP_MTU_DISCOVER and IP_PMTUDISC_DONT
33 #include <sys/socket.h> // for setsockopt()
34 #endif
35 
36 namespace nfd {
37 namespace face {
38 
40  "UnicastUdpTransport");
41 
42 UnicastUdpTransport::UnicastUdpTransport(protocol::socket&& socket,
43  ndn::nfd::FacePersistency persistency,
44  time::nanoseconds idleTimeout)
45  : DatagramTransport(std::move(socket))
46  , m_idleTimeout(idleTimeout)
47 {
48  this->setLocalUri(FaceUri(m_socket.local_endpoint()));
49  this->setRemoteUri(FaceUri(m_socket.remote_endpoint()));
50  this->setScope(ndn::nfd::FACE_SCOPE_NON_LOCAL);
51  this->setPersistency(persistency);
52  this->setLinkType(ndn::nfd::LINK_TYPE_POINT_TO_POINT);
53  this->setMtu(udp::computeMtu(m_socket.local_endpoint()));
54 
55  NFD_LOG_FACE_INFO("Creating transport");
56 
57 #ifdef __linux__
58  //
59  // By default, Linux does path MTU discovery on IPv4 sockets,
60  // and sets the DF (Don't Fragment) flag on datagrams smaller
61  // than the interface MTU. However this does not work for us,
62  // because we cannot properly respond to ICMP "packet too big"
63  // messages by fragmenting the packet at the application level,
64  // since we want to rely on IP for fragmentation and reassembly.
65  //
66  // Therefore, we disable PMTU discovery, which prevents the kernel
67  // from setting the DF flag on outgoing datagrams, and thus allows
68  // routers along the path to perform fragmentation as needed.
69  //
70  const int value = IP_PMTUDISC_DONT;
71  if (::setsockopt(m_socket.native_handle(), IPPROTO_IP,
72  IP_MTU_DISCOVER, &value, sizeof(value)) < 0) {
73  NFD_LOG_FACE_WARN("Failed to disable path MTU discovery: " << std::strerror(errno));
74  }
75 #endif
76 
77  if (getPersistency() == ndn::nfd::FACE_PERSISTENCY_ON_DEMAND &&
78  m_idleTimeout > time::nanoseconds::zero()) {
79  scheduleClosureWhenIdle();
80  }
81 }
82 
83 void
84 UnicastUdpTransport::beforeChangePersistency(ndn::nfd::FacePersistency newPersistency)
85 {
86  if (newPersistency == ndn::nfd::FACE_PERSISTENCY_ON_DEMAND &&
87  m_idleTimeout > time::nanoseconds::zero()) {
88  scheduleClosureWhenIdle();
89  }
90  else {
91  m_closeIfIdleEvent.cancel();
92  setExpirationTime(time::steady_clock::TimePoint::max());
93  }
94 }
95 
96 void
97 UnicastUdpTransport::scheduleClosureWhenIdle()
98 {
99  m_closeIfIdleEvent = scheduler::schedule(m_idleTimeout, [this] {
100  if (!hasBeenUsedRecently()) {
101  NFD_LOG_FACE_INFO("Closing due to inactivity");
102  this->close();
103  }
104  else {
105  resetRecentUsage();
106  scheduleClosureWhenIdle();
107  }
108  });
109  setExpirationTime(time::steady_clock::now() + m_idleTimeout);
110 }
111 
112 } // namespace face
113 } // namespace nfd
static time_point now() noexcept
Definition: time.cpp:79
represents the underlying protocol and address used by a Face
Definition: face-uri.hpp:44
STL namespace.
Implements Transport for datagram-based protocols.
#define NFD_LOG_FACE_INFO(msg)
Log a message at INFO level.
Definition: face-log.hpp:80
Copyright (c) 2011-2015 Regents of the University of California.
Definition: ndn-common.hpp:40
#define NFD_LOG_INCLASS_TEMPLATE_SPECIALIZATION_DEFINE(cls, specialization, name)
Definition: logger.hpp:46
EventId schedule(const time::nanoseconds &after, const Scheduler::Event &event)
schedule an event
Definition: scheduler.cpp:47
ssize_t computeMtu(const boost::asio::ip::udp::endpoint &localEndpoint)
computes maximum payload size in a UDP packet
#define NFD_LOG_FACE_WARN(msg)
Log a message at WARN level.
Definition: face-log.hpp:83